X-ray tube cooling system



Dec. 12, 1933. J B, w -rz 1,938,946

X-RAY TUBE COOLING SYSTEM Filed July 16, 1928 HEM 7x 3 (C m K 1) 1 m Patented Dec. 12, 1933 UNITED} STATES 1,938,946 X-RAY TUBE COOLING SYSTEM Julius B. Wantz, Oak Park, Ill., assignor to General Electric X-Ray Corporation, Chicago, 111., a corporation of New York Application July 16, 1928. Serial No. 293,262

1 Claim.

The present invention relates to X-ray tubes and has particularly to do with a means for dissipating the heat which is generated therein.

It contemplates a system by which the heat generated upon the focal spot of the anode of an X-ray tube, the tube preferably being of the oil-immersed type, is carried by some excellent heat-conducting element to a point at which cooling will take place. It is further contem plated that the cooling medium employed will then be brought back to the target of the tube for the absorption of an additional quantity of heat, the replacement and cooling medium being substantially if not actually continuous.

Included in the objects of the invention are the provision of the following: 1

An eflicient cooling means for the 'anode of an X-ray tube; 7

Means for absorbing heat from the anode by a medium of relatively high heat conductivity;

Means for radiating heat from the cooling medium referred to herein and returning the cooling medium to the anode of the tube;

An unique anode construction facilitating the use of a system of the variety herein described, and the employment of an unique and heretofore unused cooling medium; 7

Novel structural features adapted to facilitate the employment of the medium indicated and to provide for the rapid cooling of the target.

These, and such other objects as may here-' inafter appear, are obtained by the novel construction of the various elements which con-- stitute the single embodiment of the invention herein described and illustrated in the accompanying single sheet of drawing, in which Figure 1 is a schematic diagram of the new cooling system, a number of the parts including the electrical circuit adapted to generate the electromotive force providing the X-light, being shown in schematic form; I

Figure 2 is an enlarged longitudinal section of an anode of the character used in the tube shown in Figure 1;

Figure 3 is a transverse section along the line 3--3 of Figure 2; and

Figure 4 is a similar section of another anode suitable for the purpose described.

Generally stated, in the particular device herein described and illustrated, the cooling medium may be any suitable liquid, but the particular apparatus is devised for the employment of mercury. The anode is made hollow and the cooled mercury permitted to impinge directly behind the focal spot in the anode. As the mercury becomes heated, it expands and forces itself through a system of piping remote from the X-ray tube. In the particular structure here shown, use is made of the thermo-syphon system of circulation wherein natural circulation of the heated mercury is obtained through the expansion of the mercury itself. If necessary, any other medium may be provided for forcing circulation of such mercury, such as,'for instance, a pump, or the like. Such mediums are all well known in the art and a description here would be surplusage.

In the particular illustration of the embodiment of the invention shown herewith, the application of the invention is made directly to a tube of the oil-immersed type. I

Like reference characters are used to designate similar parts in the drawing and in the description of the invention which follows.

Reference should be had first to Figure 1. The other figures will be referred to as reference thereto becomes necessary.

In Figure 1, the container 10 is provided for a tube, a transformer, and other apparatus normally included in a tank in an oil-immersed apparatus. The container 10is closed by a cover 11.

Within the container 10 is an X-ray tube 12, having a cathode 13, and an anode 14.

Upon the anode 14'is a button or target 15. The anode includes a shank 16, and a sealing sleeve 17, there being a seal 18 between the sealing sleeve and the glass envelope of the tube.

The anode arm of the envelope about the tube is designated 19, the bulbous portion of such tube by the numeral 20, and the cathode arm 21.

Within the anode 14 is a partition 22. A reservoir of cooledmercury is designated 23. Such mercury is disposed at the far end of the anode 14 and to the rear of the partition 22. A tube or duct 24 passes through the partition 22 to allow the passage of cooled mercury forwardly in the anode 14 and againstthe wall of said anode closely adjacent to the focal spot 15.

A second tube or duct extends from the partition 22, but in the opposite direction, such tube being designated by the numeral 25, and hereinafter referred to as'the-return tube for hot mercury. At the end of the anode shank 16 is a connection 26. Leading into such connection is a tube for transferring cooled mercury to the reservoir 23, the return tube 25 passing therethrough to a heat radiating system 27 comprising a plurality of pipes in coil arrangement, the system designated generally 2'7.

In association with the system 27 is a siphon device 28 for the purpose of relieving excessive strain upon the cooling system and compensating for the expansion of the mercury due to the heat generated upon the focal spot 15.

Without the aid of a pump, an efficient and rapid flow of mercury is obtained through the cooling system described, the heated mercury being discharged through the tube 25 to the cooling system 2''! and returned to the reservoir 23, from which it is drawn as an incident to the heating of the mercury adjacent the button 15. It is to be noted that the tube 24 discharges chilled mercury in close proximity with the wall of the anode 14 adjacent the button 15 so that such portion of the anode will have the benefit at all time of the cooled mercury in the cooling system.

Referring again to Figure 1, a description of the electrical circuit employed may be given. A source of power is designated 29. In the circuit is a main switch 30, and in such circuit is an auto-transformer 31, of conventional type.

An adjustable control point 32 is provided in the auto transformer for varying. the voltage across the primary of a high-tension transformer, the primary of which is designated 33, and the secondary of which is designated 34.

A rheostat 35 for varying the voltage across the primary of a filament transformer is shown, the primary of such transformer being 36 and the secondary thereof 37.

A plurality of insulated bushings 38 are provided for passing leads through the wall of the container 10. Both of the transformers referred to are within the tank, but the control means therefor are external to such tank 10.

The system or circuit for the generation of suitable energy for the production of X-lightin a tube is quite conventional and will be found in numerous patent applications and in commercial apparatus of the present day.

While Figure 3 discloses an anode of the type illustrated in Figure 2 and in which additional radiated surface is provided by the employment of transverse corrugations or radial groovings, Figure 4 illustrates a different type of anode, the corrugations therein running longitudinally of the anode and its shank. In Figure 4, such corrugations are indicated 40, the direction of the corrugations being parallel to the axis of the anode 14.

Of course, many other forms of anode could be employed, and it is not supposed that the present' types of anode are the only one which will produce efficient results in connection with a mercury cooling system, but on the contrary; the invention is the provision of a cooling system which has a potentiality of being more efficient than water cooling, the provision of an apparatus adapted to employ mercury as a cooling medium, and the arrangement in association with an X- ray tube of a thermo-siphon cooling system for the anode of such tube.

'I claim:

In combination, a tank, an X-ray tube in said tank and having a hollow stemmed anode, tube energizing instrumentalities in said tank and operatively connected to said tube, oil in said tank and completely immersing said tube and said energizing instrumentalities, said hollow anode having an apertured transverse dam therein provided with a tube projecting forwardly of said dam to proximity with the end of the hollow section of said anode and a second tube projecting rearwardly from said dam to form a return conduit, a supply conduit connected to said anode, the return conduit and the supply conduit having therebetween a plurality of coils surrounded by the insulating oil in said tank, and mercury in said hollow anode to be circulated through said coils and conduits by the heat of said anode.

- JULIUS B. WANTZ. 

